How odd - my Bluetooth pref pane is present in the /System/Library/PreferencePanes/ folder, but it's not showing up in the System Preferences.
Instead, I get two "General" Pref panes, one under the third-party heading.
I have uControl installed.
Any leads?
-s*
Edit: it turns out that removing uControl from the /Library/PreferencePanes folder allows the Bluetooth Prefpane to show up again.
How odd.